#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n;
    string s;
    cin >> n >> s;
    mint ans = 1;
    vector<int> a;
    rep(i,n){
        if(s[i]=='1') a.push_back(i);
    }
    if(a.empty()){
        cout << 0 << endl;
        return 0;
    }
    rep(i,a.size()-1){
        int val = a[i+1] - a[i] + 1;
        ans *= val;
    }
    cout << ans.val() << endl;
    return 0;
}